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CPUSET_GETAFFINITY(2) FreeBSD System Calls Manual CPUSET_GETAFFINITY(2)
NAMEcpuset_getaffinity, cpuset_setaffinity -- manage CPU affinity
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS#include <sys/param.h>
#include <sys/cpuset.h>
intcpuset_getaffinity(cpulevel_tlevel, cpuwhich_twhich, id_tid,
size_tsetsize, cpuset_t*mask);
intcpuset_setaffinity(cpulevel_tlevel, cpuwhich_twhich, id_tid,
size_tsetsize, constcpuset_t*mask);
DESCRIPTIONcpuset_getaffinity() and cpuset_setaffinity() allow the manipulation of
sets of CPUs available to processes, threads, interrupts, jails and other
resources. These functions may manipulate sets of CPUs that contain many
processes or per-object anonymous masks that effect only a single object.
The valid values for the level and which arguments are documented in
cpuset(2). These arguments specify which object and which set of the
object we are referring to. Not all possible combinations are valid.
For example, only processes may belong to a numbered set accessed by a
level argument of CPU_LEVEL_CPUSET. All resources, however, have a mask
which may be manipulated with CPU_LEVEL_WHICH.
Masks of type cpuset_t are composed using the CPU_SET macros. The kernel
tolerates large sets as long as all CPUs specified in the set exist.
Sets smaller than the kernel uses generate an error on calls to
cpuset_getaffinity() even if the result set would fit within the user
supplied set. Calls to cpuset_setaffinity() tolerate small sets with no
restrictions.
The supplied mask should have a size of setsize bytes. This size is usu-
ally provided by calling sizeof(mask) which is ultimately determined by
the value of CPU_SETSIZE as defined in <sys/cpuset.h>.
cpuset_getaffinity() retrieves the mask from the object specified by
level, which and id and stores it in the space provided by mask.
cpuset_setaffinity() attempts to set the mask for the object specified by
level, which and id to the value in mask.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
The following error codes may be set in errno:
[EINVAL] The level or which argument was not a valid value.
[EINVAL] The mask argument specified when calling
cpuset_setaffinity() was not a valid value.
[EDEADLK] The cpuset_setaffinity() call would leave a thread
without a valid CPU to run on because the set does not
overlap with the thread's anonymous mask.
[EFAULT] The mask pointer passed was invalid.
[ESRCH] The object specified by the id and which arguments
could not be found.
[ERANGE] The cpusetsize was either preposterously large or
smaller than the kernel set size.
[EPERM] The calling process did not have the credentials
required to complete the operation.
SEE ALSOcpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2),
pthread_affinity_np(3), pthread_attr_affinity_np(3)HISTORY
The cpuset_getaffinity family of system calls first appeared in
FreeBSD 7.1.
AUTHOR
Jeffrey Roberson <jeff@FreeBSD.org>
FreeBSD 10.1 September 10, 2010 FreeBSD 10.1